Polyolefins are widely used as plastics and demonstrate superior moldability, solvent resistance and mechanical strength, possess a low specific gravity, and are inexpensive as materials in the fields of automobile parts, electric/electronic parts, electric products for domestic use, blown and cast film, molded goods, calendered and extruded profiles, and the like.
Polyolefins have been modified with various additives. For example, inert fillers, such as clays, have been added to facilitate manufacture and add economic value to the compositions. And, carbon black has been added as a colorant or as a UV protectant. In some applications it is desirable that the polyolefins are flame resistant. Accordingly, flame retardants may be added to the polyolefin to render the polyolefins flame resistant. Commonly used flame retardants include inorganic flame retardant such as magnesium hydroxide or aluminum hydroxide, halogenated flame retardants such as decabromodiphenyl ether, non-halogenated flame retardants such as ammonium carbamylpolyphosphate, or a flame retardant filler package which may be a combination of any of the above.
While polyolefins have proven to be versatile by accommodating various additives that can enhance the manufacture, processability, and/or ultimate utility of the compositions, the addition of additives can have an adverse impact on the resultant polyolefin composition. For example, polyolefins generally have limits on the level of filler materials or other particulates that can be incorporated into the composition without negatively impacting one or more characteristics of the manufacture, processability, or mechanical properties of the polyolefin composition. For example, it has been observed that polyolefin compositions that include large amounts of flame retardants have a tendency to bloom or bleed out, which is a phenomenon where small amounts of flame retardant migrate to the surface of the composition and deposit on fabrication equipment such as molds. Similarly, reduction in melt viscosity, crystallinity, decreased tensile strength and modulus, or decreased elongation and impact strength may be observed with the addition of a flame retardant package.
Accordingly, there is a need for flame retardant polyolefin compositions that have good flame resistance, good UV properties, and maintained or improved mechanical properties.